The basic unit of a prior art electrostatic precipitator includes, as shown in FIG. 1 of the drawings, a pair of parallel identical grounded plate electrodes 2 between which is disposed a pair of parallel plate anode electrodes 3 of shorter length than electrodes 2 and another grounded plate electrode 4 of the same length as that of the anode electrode 3 therebetween. A corona discharge wire electrode 1 is positioned forwardly of the grounded plate electrode 4 and biased at twice as high potential as that applied to the anode electrode 3. For actual practice, a plurality of such units is arranged successively to increase the collecting capacity of the precipitator. In this prior art construction, a stream of air is introduced from the left side or forward end of the precipitator and the dust particles contained in the air stream may become charged as they pass through the corona discharge area and then collected by the grounded or collecting plate electrodes. However, this prior art construction necessitates the use of two positive potentials which would add to the complexity of a power source and the corona discharge electrode 1 must be supported separately from the other electrodes to ensure good electrical isolation therebetween.